Thread protector



Aug. 11, 1959 E- R. SEWARD ETAL THREAD PROTECTOR Filed Feb. 13, 1957 Unite THREAD PROTECTOR Application February 13, 1957, Serial No. 639,928

7 Claims. (Cl. 138-96) This invention relates to capor sleeve-like attachments for the ends of large tube sections which may serve different purposes. For instance, such attachments can be formed as temporary or permanent carriers of working implements for machining large bores; as pillows or bases of upstanding hollow columns in scaffolding, and, most advantageously, as protecting devices for the threaded ends of oil well casing strings.

Such attachments consist mainly of sleeves or caps which can be slipped over the free ends of the tubings and locked there in position by internal locking means connected to their bases.

It is the main object of this invention to provide an improved tube and attachment which can be easily handled, with one hand only, in both assembly and disassembly, and which, in locked position, is held rigidly in perfect radial and axial alignment with the tube end, and protects threads on said tube end, for instance during transportation or hoisting.

Other objects and advantages will become apparent from a consideration of the specification and claims.

The object of the invention is achieved by providing one or several pairs or twins of locking members, whereby each member is arranged diametrically opposite to its twin and held rigidly in locking position, viz., presssed against the inner wall of the tube end, by means of a stretched toggle joint that can be manually controlled for release.

A further characteristic feature of the invention is the arrangement of these locking twins on upright posts or levers, the lower ends of which are hinged to the base of the protector body and which are operatively connected by two links forming the said toggle joint. It is an important advantage of this feature that the locking forces on the inner wall of the tube end, on the one hand, and the reactive forces on the toggle joint, on the other hand, are directly balanced against each other without being transmitted to the manually controllable means so that the shifting into, as well as out of, locking position may be performed with moderate force without an excessive effort of the one hand which operates the attachment in assembly or disassembly.

An upand downwardly movable handle bar is provided as manually operable means for the toggle joint. The upward position of this handle bar corresponds to the stretched position of the toggle joint and is secured by a spring reactive between the bar and the protector body. The downward position of the handle bar, into which it is forced against the pressure of the spring by closing the gripping hand, corresponds to the released position of the toggle joint and therefore of the locking twins.

Further objects and advantages of the invention will become obvious from the following detailed description of a special embodiment of an attachment as thread protector, accompanied by a drawing, in which Fig. 1 shows, in elevation, a threaded tube end, and

rates Patent aligned to it for assembly, a protecting device according to the invention;

Fig. 2 is a vertical section through the protecting device along lines 2-2 of Fig. 3;

Fig. 3 is a top plan view of the protecting device.

The protecting device of the invention generally designated by numeral 10, comprises a sleeveor collar-like body which can be slipped over the threaded end 11 of a tube section 12, for instance a casing string of an oil well. The inner diameter of the sleeve or collar portion 13 of protecting device 10 is dimensioned for running fit over the cylindrical surface of tube section 12, and the height of sleeve 13 is large enough not only to cover the threads in the tube end but also to cover, to a moderate extent, the cylindrical part of the tube end above the threads.

i the tube end and holding it axially and radially correctly aligned.

A traverse 17, rigidly connected to ring 14, bridges its opening and serves as a base for the locking members and their operating means, respectively. On traverse 17, the

lower ends of two oppositely arranged upright posts 18 are hinged on pivots 19. At their upper ends, the posts 18 form recesses 20, with oppositely inclined rear walls 21. Wedge-like locking members 2-2 are slidably arranged in recesses 20. For additionally guiding the locking members along the inclined rear walls 21, their lower ends are connected to pins 23 which slide in holes 24 of bottom parts 25 of recesses 20.

Springs 26 encircle pins 23 and are so arranged between the under faces of locking members 22 and the upper faces of bottom parts 25 that they tend to hold the locking members 22 in uppermost position, limited by heads 27 of pins 23 abutting the under faces of bottom parts 25.

Wedge-like locking members 22 are preferably provided with one-sided ratchet-like teeth 28, so as to increase the friction hold.

The steering of posts 18, and, therefore, of locking members 22 into locked as well as released position, is performed by a toggle joint. This toggle joint is formed by two links 29 hinged on pivots 30 to posts 18 and connected at their inner ends to a common pivot 31 of a hollow column 32. In the stretched position of the toggle joint (shown in full lines in Fig. 2) the locking members are in engagement with the inner wall of the tube end to be protected, and the forces created, balance each other directly without any reaction to steering column 32. For manually controlling the toggle joint, hollow column 32 is slidably arranged on a vertical rigid post 33, fixed with its lower end to traverse 17. A spring 34, encircling post 33 and acting between the upper face of traverse 17 and the lower face of column 32, tends to hold toggle joint 29 in stretched position and therefore the locking members 22 engaged with the inner tube wall.

As can be seen from the foregoing description, the slidable arrangement of locking members 22 in their recesses 28 allows always to bring the toggle joint 29 into complete stretched position independent of existing tolerances of the protecting device itself and the tube end, respectively.

For manual control of the toggle joint, the lower end of sliding column 32 is provided with a handle bar 35. When this handle bar is pulled downwardly, as shown in dotted lines in Fig. 2, toggle links 29 are moved into angular position to each other, so that locking members 28 swing into the released position shown in dotted lines in Fig. 2.

To operate the device, the operator puts one hand through the bottom opening of base ring 14 until the bend between the thumb and the palm of his hand abuts against traverse 17. With his other fingers, he grips handle bar 35 from above. By forcibly closing his hand, he moves toggle joint 29 and consequently locking members 22 into released position. He now can freely slip the protector over the tube end until it abuts with its rim 16 in the open mouth of the tube end. By loosening the grip of his hand, the operator allows toggle joint 29 to stretch, and locking member 22 firmly to engage the inner wall of the tube end.

For dissembly, the operator grips the protector again as described above. Holding his hand closed, he strips it from the tube end.

From the foregoing, it will be appreciated that the attachments of the invention can be handled with one hand in both assembly and disassembly, and, when secured in place, it is radially and axially accurately aligned with the tube end, and rigidly connected to it against axial as well as peripheral displacement.

We claim:

1. An attachment formed as thread protector for externally threaded pipe ends comprising a sleeve, a base ring secured to an inner end of said sleeve, the inner rim of said ring being upturned to form a seat for a threaded pipe end, at least one pair of oppositely arranged upright posts pivotally secured to said base ring, a tapered recess formed in the upper portion of said posts, wedge shaped locking members slidably arranged in said recesses, and a toggle joint operatively connected to said locking memfbers to hold said locking members in locking position when stretched and to move said locking members out of locking position when buckled.

2. The thread protector defined in claim 1 comprising spring means in said recesses acting against the lower faces of said locking members and holding said members in their uppermost position.

3. The thread protector defined in claim 1, wherein said toggle joint comprises a vertically movable column and two links pivotally connected with their inner ends to said column and with their outer ends to the upper portions of said posts.

4. A thread protector as defined in claim 3, comprising a handle bar for manual vertical displacement of said vertically movable column of the toggle joint.

5. A thread protector as defined in claim 3, comprising a stationary traverse fixed to said base ring, a stationary vertical rod fixed to said traverse and a tube sliding over said rod and forming said vertically movable column.

6. A thread protector as defined in claim 5, comprising a coil spring encircling said stationary verticalrod and forcing said vertically movable column upwardly into the stretched position of the toggle joint.

7. A thread protector for externally threaded pipe ends, comprising a sleeve, a base ring secured to an inner end of said sleeve, the inner rim of said ring being upturned to form a seat for a threaded pipe end, at least one pair of oppositely arranged upright posts pivotally secured to said base ring, tapered recesses in the upper portions of said posts, wedge-shaped locking members slidably arranged in said recesses, spring means forcing said locking members into their uppermost position, and a toggle joint actuating said posts and locking members; said toggle joint comprising a vertically movable center column, a plurality of links, of which each is pivoted with its inner end to said column and with its outer end to the upper part of one of said posts, and means for manually raising and lowering said center column, thereby moving said locking members in locking position by raising the column and stretching the links of the toggle joint, and releasing the locking members by lowering the column and folding said links.

References Cited in the file of this patent UNITED STATES PATENTS 1,600,860 Young Sept. 21, 1926 2,613,983 Knudsen Oct. 14, 1952 2,670,799 Dobbs Mar. 2, 1954 

